Contact release capsule useful for chemical mechanical planarization slurry

ABSTRACT

The invention relates to a contact release capsule comprising a particle, a chemical payload, and a polymer coating, wherein the particle is impregnated with the chemical payload, and the chemical payload is held inside the particle by the polymer coating until the contact release capsule contacts a surface and a shearing force removes the polymer coating allowing the chemical payload to release outside the particle. The contact release capsule is useful in chemical mechanical planarization slurries. Particularly, the contact release capsule may comprise a glycine impregnated silica nanoparticle coated with a polymer, wherein the contact release capsule is dispersed in an aqueous solution and used in the copper chemical mechanical planarization process. Use of the contact release capsule in a slurry for copper chemical mechanical planarization may significantly improve planarization efficiency, decrease unwanted etching and corrosion, and improve dispersion stability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/505,835, entitled “Contact Release Capsule Useful for ChemicalMechanical Planarization Slurry”, filed on Jul. 7, 2011, the contents ofwhich are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a contact release capsule comprising aparticle, a chemical payload, and a polymer coating, wherein theparticle is impregnated with the chemical payload, and the chemicalpayload is held inside the particle by the polymer coating until thecontact release capsule contacts a surface and a shearing force removesthe polymer coating allowing the chemical payload to release outside theparticle. The contact release capsule is useful in chemical mechanicalplanarization slurries.

2. Description of the Related Art

Chemical Mechanical Planarization (CMP) was first introduced in theearly 1980's by IBM as a semiconductor manufacturing process used toremove material and planarize a wafer surface. Since then, CMP hasenabled the continuous scale down of semiconductor device sizes and theintroduction of many new materials, including the use of copperinterconnects. The CMP process consists of a polishing pad and anaqueous slurry containing chemicals and abrasive nanoparticles. Thewafer surface to be planarized is rotated against the polishing padwhich is continuously supplied with slurry. The synergistic combinationof mechanical abrasion and chemical etching creates high materialremoval rates (MRR) and rapid planarization. In depth reviews of the CMPprocess can be found in the literature, for example see “NanoparticleEngineering for Chemical-Mechanical Planarization” by U. Paik and J.Park, CRC Press, Boca Raton, Fla. (2009), or “The Effects of SlurryChemistry on the Colloidal Behavior of Alumina Slurries and CopperNanohardness for Copper Chemical Mechanical Planarization”, by R.Ihnfeldt, Ph.D. Dissertation, University of California, San Diego(2008).

Currently, CMP is used on a variety of surfaces including aluminum,tungsten, various oxides and nitrides, copper, and nickel, to name afew. Despite numerous advancements in slurry technologies, significantimprovements are still needed. Commercial slurry products containingsilica, alumina, ceria, ZnO, or TiO as their abrasive nanoparticles havebeen developed over the last several decades. Manufacturers have evendeveloped composite nanoparticles of porous silica coated with ceria,colloidal alumina spotted with various metals, and metal oxide/polymernanoparticle composites, see U.S. Patent Application Publication No.2010/0258528, and U.S. Pat. No. 6,764,574, which are hereby incorporatedby reference in their entirety. Chemical components in slurries includecomplexing agents, oxidizers, corrosion inhibitors, surfactants, and alltypes of acids and bases to control the pH of the solution.

SUMMARY OF THE INVENTION

While a plethora of slurry products have been developed, no known workhas attempted to use the nanoparticle to deliver a localized chemicalpayload simultaneously with mechanical abrasion to the wafer surface.Therefore, the purpose of this invention is to significantly improve CMPslurry technology by incorporating the chemical action of the slurryinto the abrasive nanoparticle, to create a localized simultaneouschemical and mechanical action on the wafer surface.

Over the last several decades manufacturers have made tremendousimprovements in slurry nanoparticle dispersions and have tediously andmeticulously formulated a variety of slurry chemistries. In the lastseveral years, equipment and consumable manufactures have focused theirdevelopment efforts on revolutionary predicted future chip designtechnologies, such as 3D wafer level packaging (3D-WLP) and stackedintegrated circuit (3D-SIC), and thru silicon vias (TSVs), and mademinimal efforts at improving current technologies to enable thecontinued scale down of device sizes using current chip designs. One ofthe processing steps which will require further improvement to enablescale down using current manufacturing methods is copper CMP. Currently,copper CMP slurry solutions require a complexing agent, such as glycine,to maintain an adequate MRR, which at the same time, also causes staticetching and dissolution (i.e. corrosion) of the wafer surface which isdifficult to control. If the exposure of the complexing agent to thecopper surface could be controlled so that only the abraded areas wereaffected, then static etching and corrosion could be reduced oreliminated. Therefore, one aspect of this invention is to significantlyimprove current copper CMP slurry technology by combining the complexingagent into the abrasive nanoparticle, so that mechanical and chemicalactions of the slurry are localized and simultaneous, thus improvingprocessing efficiency and tolerances.

Just in the last few years there has been an enormous interest indeveloping technologies to enable the expected future chip designtechnologies (3D-WLP, 3D-SIC, TSVs, etc.). Equipment and consumablemanufacturers predict semiconductor manufacturers to move to these newtechnologies within the next decade. Companies like Sinmat Inc. havedeveloped numerous revolutionary CMP slurries to tackle the toughmaterials (SiC, GaN, Diamond, etc.) required for future chip designs, ashave many equipment and other CMP consumable manufacturers, such aspsiloQuest Inc., see U.S. Patent Application Publication Nos.20100258528, and 20050055885, which are hereby incorporated by referencein their entirety. As of yet, however, many semiconductor manufacturershave been reluctant to implement the new chip designs as the cost ofownership is just too high, requiring new tool and consumable sets, andunproven processes. Herein lies the problem. While chip manufacturerswould like to continue the incremental scale down of their product asthey have in the past, with minimal process and tool set changes,equipment manufacturers have focused all their development efforts onthese revolutionary future chip designs, leaving a gap between what isneeded and what is available. This has left many chip manufacturers tofend for themselves, basically developing their own CMP slurries, andmodifying tool sets themselves. Because of this, a significant potentialmarket exists for suppliers with products that will allow chipmanufacturers to continue processing using current methods, versusforcing them to implement new unproven processes. Improvements in CMPslurry technologies to improve current processing tolerances andefficiency, would be very valuable to chip manufacturers as it wouldenable the most economical solution to continue scale down of theirproduct. Furthermore, even the new chip designs (3D-SIC) will stillrequire many of the same CMP processing steps (like copper CMP) but theywill need to maintain tighter tolerances, so having the ability toperform these steps using current tool sets will be a very attractiveoption for chip manufacturers.

Therefore, the present invention provides a revolutionary technology tosignificantly improve CMP slurries. An embodiment of the inventioncomprises a contact release capsule, wherein the contact release capsulecomprises a particle, a chemical payload, and a polymer coating. In anembodiment, the particle comprises a pore or pores which can beimpregnated with a chemical payload. In an embodiment, the chemicalpayload remains contained in the particle due to the polymer coatingwhich is present on the outside surface of the particle. In anembodiment, when the particle contacts a surface and a pre-specifiedshearing force occurs, the polymer coating is removed, and the chemicalpayload is free to move away from the particle and into the outsideenvironment.

CMP slurries typically comprise nano-sized abrasive particles dispersedin an aqueous solution. In an embodiment of the contact release capsule,the particle comprises a metal, a metal oxide, a polymer, and/or acomposite made of combinations thereof.

In an embodiment of the contact release capsule, the particle isselected from the group consisting of fumed or colloidal silica, fumedor colloidal alumina, ceria, MnO₂, ZnO, TiO, any polymer material,and/or combinations thereof.

The particle may be any shape. In an embodiment, the particle isspherical.

In an embodiment, the particle may also be a single walled carbonnanotube or a multi-walled carbon nanotube, wherein the inside tube ofthe single or multi-walled nanotube is the pore of the particle in whicha chemical payload can be impregnated.

The contact release capsule may be a variety of sizes. The particle maybe a variety of sizes, and the thickness of the polymer coating may alsobe a variety of sizes. In an embodiment, the size of the contact releasecapsule is in the range of about 1 nm to about 1 mm. In an embodiment,the size of the contact release capsule is in the range of about 10 nmto about 1 μm. In an embodiment, the size of the particle is in therange of about 1 nm to about 1 mm. In an embodiment, the size of theparticle is in the range of about 10 nm to about 1 μm.

The particle comprises a pore or pores wherein the chemical payload canbe impregnated. The pore or pores of the particle are essentially thestorage space for the chemical payload. Particles with high porosity canbe impregnated with a larger quantity of chemical payload, whileparticles with low porosity will contain less chemical payload. In anembodiment, the particle has a porosity in the range of about 0.01 cm³/gto about 0.5 cm³/g.

In the contact release capsule, the particle is impregnated with achemical payload that is a chemical compound. In an embodiment, thechemical payload is an organic or inorganic compound. In an embodiment,the chemical payload comprises a complexing agent selected from thegroup consisting of an organic polymer, alkaline agent, or organicamine. In an embodiment, the chemical payload is a compound selectedfrom the group consisting of glycine,ethylene-diamine-tetra-acetic-acid, alanine, phthalic acid, citric acid,oxalic acid, acetic acid, tartaric acid, succinic acid, amino acid,ammonium hydroxalate, lactic acid, carboxyl group, amine group, and/orcombinations thereof.

It may be desirable to use a chemical payload that reacts with thesurface of the wafer during CMP. For CMP slurries that are aqueousbased, it may be desirable to utilize a chemical payload which issoluble in water, such that it can react with the surface of the waferduring CMP. In an embodiment, the chemical payload is soluble in water.The solubility of the chemical payload in water may vary from 0.001 g/Lto 100 g/L.

In an embodiment, the polymer coating comprises at least one moiety of arepeating unit selected from the group consisting of polyacrylate,polymethacrylate, polyethyleneglycol, poly-L-lysine, poly-vinyl alcohol,polysaccharides, polyethylene, polypropylene, poly-vinyl acetate,polyisoprene, and/or any combination thereof.

In an embodiment, the polymer coating is a smart polymer. In anembodiment, the polymer coating is poly(N-isopropylacrylamide) orpoly(N-isopropylmethacrylamide).

It may be desirable to enhance stability of the contact release capsulein a liquid by utilizing a polymer which helps keep the contact releasecapsule dispersed in the liquid. In an embodiment, the polymer coatingis hydrophobic. In an embodiment, the polymer coating is hydrophilic.

In an embodiment, the chemical payload is sealed inside the particle bythe polymer coating such that liquids or gases cannot penetrate thepolymer coating. In an embodiment, the chemical payload is in the formof a solid substance inside the particle.

In an embodiment, the polymer coating is designed to allow a liquid or agas which is outside of the capsule, the ability to penetrate throughit, but not allow the molecules of the chemical payload to penetratethrough the polymer coating, therein allowing the chemical payload tosolubilize in the liquid or gas inside of the particle without lettingthe chemical payload escape until the polymer coating is removed duringcontact shearing with a surface.

In an embodiment, the thickness of the polymer coating on the capsule isin the range of about 0.1 nm to about 1 mm. In an embodiment, thethickness of the polymer coating on the capsule is in the range of about1 nm to about 1 μm.

The contact release capsule is useful in CMP slurries. Therefore afurther aspect of the invention provides a slurry comprising a mixtureof the contact release capsules, as disclosed herein, and a liquidsolution.

CMP slurries are typically aqueous based. In an embodiment of theslurry, the liquid solution comprises water.

There are several methods that can be used to disperse colloids orparticles into solution. In an embodiment, the contact release capsulesare dispersed into the liquid solution by ultrasonication.

The pH of the slurry is an important parameter during CMP, as thiscontrols the reactions that occur in the slurry and on the wafersurface. In an embodiment, the slurry further comprises an acid or baseto obtain the desired pH. In an embodiment, an acid such as H₂SO₄, HCl,HF, Citric acid, acetic acid, or tartaric acid, is used to adjust the pHto a value lower than 7.0. In an embodiment, a base such as Sodiumhydroxide, Potassium hydroxide, ammonia, Barium hydroxide, Caesiumhydroxide, Strontium hydroxide, Calcium hydroxide, Magnesium hydroxide,Lithium hydroxide, or Rubidium hydroxide, is used to adjust the pH to avalue higher than 7.0.

In an embodiment, the slurry pH is in the range of about 1.0 to about12.0.

The amount of contact release capsules in the slurry may vary. In anembodiment, the contact release capsules are dispersed into the liquidsolution in a concentration of about 0.01 wt % to about 99.0 wt %. In anembodiment, the contact release capsules are dispersed into the liquidsolution in a concentration of about 1.0 wt % to about 40 wt %.

CMP slurries typically have a variety of chemical components in them. Inan embodiment, the slurry further comprises a complexing agent. In anembodiment, the slurry further comprises an oxidizer. In an embodiment,the oxidizer is selected from the group consisting of peroxide, oxalicacid, and/or combinations thereof. In an embodiment, the slurry furthercomprises a corrosion inhibitor. In an embodiment, the corrosioninhibitor is selected from the group consisting of benzotriazole,3-amino-triazole, potassium iodate, and/or combinations thereof. In anembodiment, the slurry further comprises a surfactant. In an embodiment,the surfactant is selected from the group consisting ofsodium-dodecyl-sulfate, cetyltrimethyl-ammonium-bromide, carboxylicacid, polyacrylic acid, and/or combinations thereof.

There are a variety of techniques that may be employed to manufacturethe contact release capsules, disclosed herein. Therefore, a furtheraspect of the invention is a method of manufacturing the contact releasecapsules. An embodiment of a method of manufacturing the contact releasecapsules, as disclosed herein, comprises the steps of 1) synthesizingporous particles 2) impregnating the particles with the chemical payload3) coating the particles with a polymer.

In an embodiment of the method, the porous particles are synthesizedusing a Stober method, and/or a modification thereof.

In an embodiment of the method, the particles are impregnated using anincipient wetness technique, and/or a modification thereof.

In an embodiment of the method, the particles are coated using a freeradical polymerization technique, and/or a modification thereof.

CMP slurries are used to planarize and/or polish a wafer surface.Therefore, a further aspect of the invention is a method of planarizingand/or polishing a wafer surface comprising performing the chemicalmechanical planarization process, wherein the slurry utilized in theprocess is any of the slurries as disclosed herein. In an embodiment ofthe method, the wafer surface to be planarized and/or polished comprisesa metal, a metal oxide, an oxide, a nitride, a polymer material, and/orany combination thereof. In an embodiment of the method, the wafersurface comprises Copper, Tungsten, Tantalum, Tin, Tantalum nitride,Silicon nitride, Aluminum, Nickel, Nickel Phosphor, Nickel nitride,Silver, Gold, Platinum, Ruthenium, and/or any combination thereof. In anembodiment of the method, the wafer surface comprisestetraethylorthosilicate, Ni₃Si₄, silica, diamond, SiC, polysilicon,and/or any combination thereof. In an embodiment of the method, thechemical mechanical planarization process is Copper CMP, shallow trenchisolation CMP, Tungsten CMP, interlayer dielectric CMP, or polysiliconCMP.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Schematic representation of an embodiment of the Contact ReleaseCapsule.

FIG. 2 Schematic of the Copper CMP process.

FIG. 3 Potential-pH diagram for the a) copper-water and b)copper-water-glycine systems at total dissolved copper activity of 10⁻⁴Mand a total glycine activity of 0.1M at 25° C. and 1 atm.

FIG. 4 Schematic of typical Copper CMP mechanisms during processing.

FIG. 5 Schematic of removal mechanism for the contact release capsuletechnology in a copper CMP slurry.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a novel innovation to significantlyimprove CMP slurries. During CMP, the wafer surface to be planarized isrotated against a polishing pad, typically a polymer material, and anaqueous based slurry containing nanoparticles is continuously dispersedonto the polishing pad. Researchers have concurred that the majority ofthe removal from the wafer surface occurs due to solid-solid contact ofthe abrasive particle with the wafer surface, that is, the abrasiveparticle is embedded into the polishing pad and the wafer surfaced ispressed down onto the pad containing the embedded particle. Plasticdeformation of the wafer surface occurs as the abrasive particle indentsinto the wafer surface, and the rotating action of the wafer creates ashearing force against the particle, causing the particle to deform andremove material on the wafer surface. The focus of the disclosedinvention exploits this phenomena by creating a particle which has theability to not only provide mechanical action on the wafer surface, butto also provide a chemical action.

An embodiment of the invention comprises a contact release capsule,wherein the contact release capsule comprises a particle, a chemicalpayload, and a polymer coating. In an embodiment, the particle comprisesa pore or pores which can be impregnated with a chemical payload. In anembodiment, the chemical payload remains contained in the particle dueto the polymer coating which is present on the outside surface of theparticle. In an embodiment, when the particle contacts a surface and apre-specified shearing force occurs, the polymer coating is removed, andthe chemical payload is free to move away from the particle and into theoutside environment. The contact release capsule is useful in CMPslurries. It allows a localized and simultaneous mechanical and chemicalaction on the wafer surface.

FIG. 1 shows a schematic representation of an embodiment of the ContactRelease Capsule prior to encountering a shearing contact force with awafer surface. The particle 1 has pores 2 which can be impregnated witha chemical payload 3, and the particle is encapsulated by a polymercoating 4. When the particle contacts a wafer surface and a shearingforce occurs, the polymer coating is removed, and the chemical payloadis exposed to the wafer surface and outside environment.

CMP slurries typically comprise nano-sized abrasive particles dispersedin an aqueous solution. In an embodiment of the contact release capsule,the particle comprises a metal, a metal oxide, a polymer, and/or acomposite made of combinations thereof.

In an embodiment of the contact release capsule, the particle isselected from the group consisting of fumed or colloidal silica, fumedor colloidal alumina, ceria, MnO₂, ZnO, TiO, any polymer material,and/or combinations thereof.

The particle may be any shape. In an embodiment, the particle isspherical.

In an embodiment, the particle may also be a single walled carbonnanotube or a multi-walled carbon nanotube, wherein the inside tube ofthe single or multi-walled nanotube is the pore of the particle in whicha chemical payload can be impregnated.

The contact release capsule may be a variety of sizes. The particle maybe a variety of sizes, and the thickness of the polymer coating may alsobe a variety of sizes. In an embodiment, the size of the contact releasecapsule is in the range of about 1 nm to about 1 mm. In an embodiment,the size of the contact release capsule is in the range of about 10 nmto about 1 μm. In an embodiment, the size of the particle is in therange of about 1 nm to about 1 mm. In an embodiment, the size of theparticle is in the range of about 10 nm to about 1 μm.

The particle comprises a pore or pores wherein the chemical payload canbe impregnated. The pore or pores of the particle are essentially thestorage space for the chemical payload. Particles with high porosity canbe impregnated with a larger quantity of chemical payload, whileparticles with low porosity will contain less chemical payload. In anembodiment, the particle has a porosity in the range of about 0.01 cm³/gto about 0.5 cm³/g.

In the contact release capsule, the particle is impregnated with achemical payload that is a chemical compound. In an embodiment, thechemical payload is an organic or inorganic compound. In an embodiment,the chemical payload comprises a complexing agent selected from thegroup consisting of an organic polymer, alkaline agent, or organicamine. In an embodiment, the chemical payload is a compound selectedfrom the group consisting of glycine,ethylene-diamine-tetra-acetic-acid, alanine, phthalic acid, citric acid,oxalic acid, acetic acid, tartaric acid, succinic acid, amino acid,ammonium hydroxalate, lactic acid, carboxyl group, amine group, and/orcombinations thereof.

It may be desirable to use a chemical payload that reacts with thesurface of the wafer during CMP. For CMP slurries that are aqueousbased, it may be desirable to utilize a chemical payload which issoluble in water, such that it can react with the surface of the waferduring CMP. In an embodiment, the chemical payload is soluble in water.The solubility of the chemical payload in water may vary from 0.001 g/Lto 100 g/L.

In an embodiment, the polymer coating comprises at least one moiety of arepeating unit selected from the group consisting of polyacrylate,polymethacrylate, polyethyleneglycol, poly-L-lysine, poly-vinyl alcohol,polysaccharides, polyethylene, polypropylene, poly-vinyl acetate,polyisoprene, and/or any combination thereof.

In an embodiment, the polymer coating is a smart polymer. In anembodiment, the polymer coating is poly(N-isopropylacrylamide) orpoly(N-isopropylmethacrylamide).

It may be desirable to enhance stability of the contact release capsulein a liquid by utilizing a polymer which helps keep the contact releasecapsule dispersed in the liquid. In an embodiment, the polymer coatingis hydrophobic. In an embodiment, the polymer coating is hydrophilic.

In an embodiment, the chemical payload is sealed inside the particle bythe polymer coating such that liquids or gases cannot penetrate thepolymer coating. In an embodiment, the chemical payload is in the formof a solid substance inside the particle.

In an embodiment, the polymer coating is designed to allow a liquid or agas which is outside of the capsule, the ability to penetrate throughit, but not allow the molecules of the chemical payload to penetratethrough the polymer coating, therein allowing the chemical payload tosolubilize in the liquid or gas inside of the particle without lettingthe chemical payload escape until the polymer coating is removed duringcontact shearing with a surface.

In an embodiment, the thickness of the polymer coating on the capsule isin the range of about 0.1 nm to about 1 mm. In an embodiment, thethickness of the polymer coating on the capsule is in the range of about1 nm to about 1 μm.

The contact release capsule is useful in CMP slurries. Therefore afurther aspect of the invention provides a slurry comprising a mixtureof the contact release capsules, as disclosed herein, and a liquidsolution.

CMP slurries are typically aqueous based. In an embodiment of theslurry, the liquid solution comprises water.

There are several methods that can be used to disperse colloids orparticles into solution. In an embodiment, the contact release capsulesare dispersed into the liquid solution by ultrasonication.

The pH of the slurry is an important parameter during CMP, as thiscontrols the reactions that occur in the slurry and on the wafersurface. In an embodiment, the slurry further comprises an acid or baseto obtain the desired pH. In an embodiment, an acid such as H₂SO₄, HCl,HF, Citric acid, acetic acid, or tartaric acid, is used to adjust the pHto a value lower than 7.0. In an embodiment, a base such as Sodiumhydroxide, Potassium hydroxide, ammonia, Barium hydroxide, Caesiumhydroxide, Strontium hydroxide, Calcium hydroxide, Magnesium hydroxide,Lithium hydroxide, or Rubidium hydroxide, is used to adjust the pH to avalue higher than 7.0.

In an embodiment, the slurry pH is in the range of about 1.0 to about12.0.

The amount of contact release capsules in the slurry may vary. In anembodiment, the contact release capsules are dispersed into the liquidsolution in a concentration of about 0.01 wt % to about 99.0 wt %. In anembodiment, the contact release capsules are dispersed into the liquidsolution in a concentration of about 1.0 wt % to about 40 wt %.

CMP slurries typically have a variety of chemical components in them. Inan embodiment, the slurry further comprises a complexing agent. In anembodiment, the slurry further comprises an oxidizer. In an embodiment,the oxidizer is selected from the group consisting of peroxide, oxalicacid, and/or combinations thereof. In an embodiment, the slurry furthercomprises a corrosion inhibitor. In an embodiment, the corrosioninhibitor is selected from the group consisting of benzotriazole,3-amino-triazole, potassium iodate, and/or combinations thereof. In anembodiment, the slurry further comprises a surfactant. In an embodiment,the surfactant is selected from the group consisting ofsodium-dodecyl-sulfate, cetyltrimethyl-ammonium-bromide, carboxylicacid, polyacrylic acid, and/or combinations thereof.

There are a variety of techniques that may be employed to manufacturethe contact release capsules, disclosed herein. Therefore, a furtheraspect of the invention is a method of manufacturing the contact releasecapsules. An embodiment of a method of manufacturing the contact releasecapsules, as disclosed herein, comprises the steps of 1) synthesizingporous particles 2) impregnating the particles with the chemical payload3) coating the particles with a polymer.

In an embodiment of the method, the porous particles are synthesizedusing a Stober method, and/or a modification thereof.

In an embodiment of the method, the particles are impregnated using anincipient wetness technique, and/or a modification thereof.

In an embodiment of the method, the particles are coated using a freeradical polymerization technique, and/or a modification thereof.

CMP slurries are used to planarize and/or polish a wafer surface.Therefore, a further aspect of the invention is a method of planarizingand/or polishing a wafer surface comprising performing the chemicalmechanical planarization process, wherein the slurry utilized in theprocess is any of the slurries as disclosed herein. In an embodiment ofthe method, the wafer surface to be planarized and/or polished comprisesa metal, a metal oxide, an oxide, a nitride, a polymer material, and/orany combination thereof. In an embodiment of the method, the wafersurface comprises Copper, Tungsten, Tantalum, Tin, Tantalum nitride,Silicon nitride, Aluminum, Nickel, Nickel Phosphor, Nickel nitride,Silver, Gold, Platinum, Ruthenium, and/or any combination thereof. In anembodiment of the method, the wafer surface comprisestetraethylorthosilicate, Ni₃Si₄, silica, diamond, SiC, polysilicon,and/or any combination thereof. In an embodiment of the method, thechemical mechanical planarization process is Copper CMP, shallow trenchisolation CMP, Tungsten CMP, interlayer dielectric CMP, or polysiliconCMP.

In an embodiment, the invention comprises a copper CMP slurry containingglycine impregnated silica nanoparticles capable of localizedsimultaneous abrasion and dissolution of the copper surface. In anembodiment, the polymer encapsulated glycine impregnated nanoparticlesrelease the copper complexing agent (glycine) only upon contact with thewafer surface, a nano sized contact release capsule (herein referred toas nano-CRC). The advantages of using the contact release capsule, asdisclosed herein, in copper CMP slurries include the following:

-   -   1) Increasing planarization efficiency (ratio of step height        reduction and removed layer thickness) by decreasing surface        dissolution—This will reduce dishing and erosion of the copper        wiring and decrease the amount of Cu overfill required incoming        to Cu CMP.    -   2) Eliminating a majority of the chemical additives that are        currently required in copper CMP slurries    -   3) Reducing particle agglomeration by improving the dispersion        stability, which also controls the MRR        These advantages ultimately lead to a reduction in the cost of        CMP processing while also improving processing tolerances.

Copper CMP is a complex process because of the highly reactive nature ofthe copper surface. The most common copper CMP slurries use colloidalsilica abrasive particles dispersed in aqueous solutions that contain anoxidizer, as well as a complexing agent and corrosion inhibiting agentsand other chemicals. FIG. 2 illustrates the standard Cu CMP process.

Researchers have concurred that the mechanism of removal of the copperduring CMP involves oxidation of a thin layer of the copper surface,which is then easily abraded by the nanoparticle, followed by immediateoxidation of the newly exposed copper, as described in the followingliterature “Effect of CMP Slurry Chemistry on Copper Nanohardness”, R.V. Ihnfeldt and J. B. Talbot, J. Electrochemical Soc., 155, H412 (2008).The pH and chemistry of the slurry solution must be controlled to allowquick formation of the copper oxide film on the wafer surface. Typicallyan oxidizer, such as hydrogen peroxide, is added to increase the rate offormation of the copper oxide film. To facilitate a high MRR, acomplexing agent, such as glycine is required. FIG. 3 compares thepotential-pH diagrams of the copper-water system and thecopper-water-glycine system, showing that for the majority of CMP slurryconditions (pH 3-8), when glycine is present in the system, the mostthermodynamically stable form is the soluble copper-glycine complex,CuHL²⁺, CuL⁺, CuL₂, and CuL₂ ⁻, where L is H₂NCH₂COO. The reactionmechanisms for acidic, neutral, and basic conditions have been presentedin detail in “Effect of CMP Slurry Chemistry on Copper Nanohardness”, byR. V. Ihnfeldt and J. B. Talbot, and are summarized as follows:

-   -   1) Passivation of the copper surface to form an oxide or        hydroxide    -   2) Complex formation with glycine to form a solid copper-glycine        substance    -   3) Dissolution of the copper-glycine substance

The complexing agent quickly reacts with the copper oxide once it isformed on the surface to dissolve it into solution. Unfortunately,because the complexing agent is exposed to the entire copper surface,corrosion or dissolution of the copper surface often occurs in unwantedplaces, and increases the potential for dishing and erosion of thecopper wiring. This dissolution also decreases the planarizationefficiency and requires an increase in the incoming copper platingthickness in order to accommodate for it, which adds cost to the waferprocessing. A corrosion inhibitor is sometimes added to prevent thedissolution, but this tends to prevent the glycine-copper oxide complexreaction, and decreases the MRR. Further compounding these issues isthat all these chemical additives increase the ionic strength of thesolution and destabilize the nanoparticle dispersion, so that asurfactant may be required to prevent agglomeration of the particles,also see S. Pandija, D. Roy, and S. V. Babu, in “MicroelectronicEngineering”, 86, 367 (2009). FIG. 4 illustrates the typical mechanismsthat occur during standard copper CMP processing.

It should also be noted that abrasive-free solutions have also beendeveloped for copper CMP, which are typically used when the underlyingmaterial is a fragile “low-k” material. However, these abrasive-freeprocesses require special pads and conditioners, and are slower (lowerMRRs) than the slurries utilizing abrasives. They may even require thepurchase of a new CMP tool to perform (i.e. an electro-CMP or ECMPtool), thus, many manufacturers are reluctant to use abrasive-freesolutions unless it is absolutely necessary. Because the abrasive-freeprocesses are so expensive, many manufacturers have even found tougher“low-k” materials that are compatible with a traditional abrasivepolish.

Many of the issues occurring during copper CMP are due to the disconnectbetween the complexing chemical action and the abrasive mechanicalaction, that is, the complexing agent acts on the wafer globally, whilethe mechanical abrasion is a localized action. By combining thecomplexing agent into the nanoparticles, these issues can be eliminated.FIG. 5 illustrates the mechanism of the nano-CRC technology, asdisclosed herein, used in a copper CMP slurry. The copper surface issimultaneously mechanically and chemically removed when contacted by theglycine impregnated nanoparticle. The abraded copper pieces areimmediately dissolved into solution by the glycine. The glycine does notaffect any other part of the copper surface, eliminating the need foradditional chemicals (i.e. corrosion inhibitors and surfactants).

A method for manufacturing the contact release capsule is disclosedherein. In an embodiment, the silica nanoparticles can be synthesizedusing a similar method to that developed by Choi et al. K. S. Choi, R.Vacassy, N. Bassim, and R. K. Singh, Mat. Res. Soc. Symp. Proc., 671(2001). This is a modified Stober method, a precipitation techniquebased on controlled hydrolysis of a silicon alkoxide in a mixture ofethanol, aqueous ammonia and water. Choi et al. found that the additionof glycerol to the water/ammonia/ethanol mixture produces porous silicananospheres, where the concentration of the glycerol in the mixture canbe adjusted to get the desired porosity. Using this method silicananoparticles with wide range of porosities are possible. In anembodiment, silica nanoparticles with porosities of up to ˜0.1 cm³/g aresynthesized. In an embodiment, silica nanoparticles with porosities ofup to ˜0.2 cm³/g are synthesized. In an embodiment, silica nanoparticleswith porosities of up to ˜0.3 cm³/g are synthesized. In an embodiment,silica nanoparticles with porosities of up to ˜0.4 cm³/g aresynthesized. In an embodiment, silica nanoparticles with porosities ofup to ˜0.5 cm³/g are synthesized. In an embodiment, silica nanoparticleswith porosities of up to ˜0.6 cm³/g are synthesized.

In an embodiment, after synthesis of the porous nanoparticles, thesolvent is dried off, leaving the porous nanoparticles in powder formfor impregnation.

In an embodiment, impregnation of the silica nanoparticles is done bythe incipient wetness technique. In an embodiment, this method requiresdissolving the impregnate into an aqueous or organic solvent. Then theimpregnate-containing solution is added to the support materialcontaining the same pore volume as the volume of solution that wasadded. Capillary action draws the impregnate solution into the pores.The support material can then be dried and calcined to drive off thevolatile components within the solution, depositing the impregnate inthe pores of the support material. The maximum loading is limited by thesolubility of the impregnate in the solvent. Singh et al. havesuccessfully impregnated silica and alumina nanoparticles with a varietyof organic compounds using the incipient wetness technique, see theliterature B. Singh, A. Saxena, A. K. Nigam, K. Ganesan, and P. Pandey,J. Hazardous Materials, 161, 933 (2009). One important aspect toconsider when impregnating the nanoparticles with glycine is the optimalloading volume. Singh et al. easily loaded their nanoparticles up to 15wt % with the various chemicals. However, the effect of the glycineloading on the copper CMP process will need to be considered. Puttingtoo much glycine in the particles may cause the particles to settle, orcreate uncontrollable localized etching on the wafer surface duringpolishing. If too little glycine is impregnated into the particles,planarization efficiency and MRR may be too low.

In an embodiment, the nanoparticle loading with glycine is comparable tothe concentration of typical copper CMP slurries. For example, typicalconcentrations of glycine in copper CMP slurries range from ˜0.01-0.2M,with the concentration of abrasives in the slurry ranging from 1-20 wt%, see Modeling Material Removal Rates for Copper CMP Using CopperNanohardness and Etch Rates, R. V. Ihnfeldt and J. B. Talbot, J.Electrochemical Soc., 155, H582 (2008). Considering a standard copperCMP slurry with 0.1M glycine and 10 wt % silica, a 1 L solution contains˜7.5 g of glycine and ˜130 g of silica. Using the synthesized poroussilica nanoparticles at the same concentration (10 wt %) with a porosityof ˜0.1 cm³/g, then ˜13 cm³ of volume is available inside the silicaparticles for impregnation. Using the incipient wetness technique themaximum loading volume of the glycine is limited by the solubility ofthe glycine in the chosen solvent.

In an embodiment, the chosen solvent for impregnation is water. Inwater, the solubility of glycine is ˜25 g/100 ml, which would allow ˜3.3g of glycine to be loaded into the 130 g of silica. In an embodiment,use of a much stronger solvent, such as dimethylsulfoxide (DMSO) orchloroform, will allow for increased loading with glycine solubilitiesof ˜37 g/100 ml of DMSO and ˜46 g/100 ml of chloroform. Therefore, it ispossible to incorporate a comparable amount of glycine into the silicananoparticles as that found in standard copper CMP slurries. Thestronger solvents (DMSO, chloroform, etc.) can also be used to obtainhigher loading volumes of glycine, however, they may require the use ofa rotary evaporator or lyophilizer to dry off the solvent. Thesemachines are quite common and used often by pharmaceutical manufacturersto dry drug compounds. Obviously, increasing the porosity of thesynthesized silica allows for more glycine loading, possibly using moreeasily evaporated solvents, such as ethanol or methanol. However, itshould be noted that the optimal amount of glycine required in thecontact release capsule for a copper CMP slurry may be comparably lessthan that required in standard slurries as the localized glycineconcentration at the particle surface is much higher. The high glycineconcentration at the particle surface is exactly where the glycine isneeded when it contacts the wafer surface.

CMP slurries consist of aqueous dispersions of nanoparticles, therefore,the contact release capsules must be dispersed in water to be used inthe CMP process. Glycine is highly soluble in water, and therefore, apolymer coating of the impregnated particle must be done to prevent thehydration of the silica nanoparticles and dissolution of glycine.Obviously, if the glycine dissolves out of the particle and intosolution prior to contacting the wafer surface during CMP, then theslurry would have no new advantages over current CMP slurrytechnologies.

There are many processes available for coating particles. Typicalliquid-phase coating processes include reverse micelles method, liquidprecipitation method, and sol-gel method. Gas-phase coating methods suchas chemical vapor deposition, physical vapor deposition, and plasmacoating are also available, but with much higher operating costs, see Y.S. Chung, S. A. Song, and S. B. Park, Colloids and Surfaces A:Physicochem. Eng. Aspects, 236, 73 (2004). Many researchers have alsodeveloped new techniques for coating nanoparticles. Wang et al.developed a method to encapsulate nanoparticles in a polymer using asupercritical anti-solvent process, see Y. Wang, R. N. Dave, and R.Pfeffer, Journal of Supercritical Fluids, 28, 85 (2004). Additionally,Chung et al. successfully created hydrophobic silica nanoparticles usingan aerosol spray reactor process.

One aspect to consider is that the coating or surfactant must be stableenough to last at least one year, that is, completely insoluble in waterand non-degradable. Typical slurry shelf-life is between 1 and 3 yearsand the products are sold pre-dispersed and ready for use. It may bepossible to develop a slurry which sells as a dry powder and isdispersed just before use, but this would be much more difficult tocommercialize as manufacturers are reluctant to change, and it wouldstill need to be stable for at least 24 hours or the cost of labor tocontinually manage the mixing will be too high.

Furthermore, the coating or surfactant must be easily penetrable whenthe particle comes into contact with the wafer surface, so that theglycine is easily released when needed. Previous work determined theshear force on a 200 nm abrasive particle during a typical copper CMPprocess is ˜3.6×10⁻¹⁰N (this is with a wafer down force of ˜1 psi), seeModeling of Copper CMP Using the Colloidal Behavior of an Alumina Slurrywith Copper Nanoparticles, R. Ihnfeldt and J. Talbot, J. ElectrochemicalSoc., 154, H1018 (2007). So the shearing strength of the coating needsto be just less than this number to allow release of the glycine uponcontact with the copper wafer surface. Additionally, the chosen coatingprocess must maintain the integrity of the impregnated nanoparticles(i.e. no solvents can be used during the coating process in whichglycine is soluble).

In an embodiment a polymer coating is used to encapsulate theimpregnated nanoparticles. Recently, polymer coating of magneticnanoparticles has sparked much interest in the biotechnology field dueto the possible use of these particles in targeted drug deliverysystems, magnetic resonance imaging, and DNA and RNA separation.Researchers typically utilize a free radical polymerization method tocoat the nanoparticles with the desired polymer, see S. R. Bhattarai, R.B. Kc, S. Y. Kim, M. Sharma, M. S. Khil, P. H. Hwang, G. H. Chung, andH. Y. Kim, Journal of Nanobiotechnology, 6, 1 (2008). This methodinvolves the creation of free radical monomer units, which then rapidlygrow polymer chains with the successive addition of polymer buildingblocks. Numerous experimental procedures and techniques for radicalpolymerization are defined in the literature, see K. Matyjaszewski andT. P. Davis, Handbook of Radical Polymerization, Hoboken:Wiley-Interscience (2002), and T. Wang and J. L. Keddie, Advances inColloid and Interface Science, 147-148, 319 (2009). Korolyov andMogilevich estimate more than 400 publications devoted to new freeradical polymerization methods appeared between 2004-2007, whichillustrates the enormous growth within this area of science, see G. V.Korolyov and M. M. Mogilevich, Three Dimensional Free-RadicalPolymerization, Springer-Verlag, Berlin Heidelburg (2009). Additionally,several methods to polymer coat nanoparticles using radicalpolymerization have been detailed in the literature including the use ofpolyethyleneglycol (PEG), poly-L-lysine (PLL), poly-vinyl alcohol (PVA),and polysaccharides, see Y. Zhang and J. Zhang, Journal of Colloid andInterface Science, 283, 352 (2005), H. S. Lee, E. H. Kim, H. Shao, andB. K. Kwak, Journal of Magnetic Materials, 293, 102 (2005), J. S. Kin,T. J. Yoon, K. N. Yu, M. S. Noh, M. Woo, B. G. Kim, K. H. Lee, B. H.Sohn, S. B. Park, J. K. Lee, and M. H. Cho, Journal of VeterinaryScience, 7, 321 (2006), R. Trehin, J. L. Figueiredo, M. J. Pittet, R.Weissleder, L. Josephson, and U. Mahmood, Neoplasia, 8, 302 (2006), andJ. H. Clement, M. Schwalbe, N. Buske, K. Wagner, M. Schnabelrauch, P.Gornert, K. O. Kliche, K. Pachmann, W. Weitschies, and K. Hoffken,Journal of Cancer Research and Clinical Oncology, 132, 287 (2006).Bhattarai et al. successfully coated iron oxide nanoparticles withN-hexanoyl chitosan. Herrera et al. coated cobalt ferrite nanoparticleswith poly(N-isopropylacrylamide) (pNIPAM) andpoly(N-isopropylmethacrylamide) (pNIPMAM) and showed the coatedparticles were actually less agglomerated in aqueous solutions thannon-polymer coated particles, see A. P. Herrera, C. Barrera, Y. Zayas,and C. Rinaldi, Journal of Colloid and Interface Science, 342, 540(2010). One of the difficulties that has been encountered with usingimpregnated and polymer coated nanoparticles for drug delivery is thepoor stability of these particles in solution. It is important to note,however, that the drug delivery products usually employ a timed releasemechanism, while the nano-CRC release mechanism is physical abrasivecontact with the wafer surface during CMP. This type of mechanicalrelease mechanism will allow for the use of much tougher, and/or thickerpolymer coatings, which will enable the particles to be much more stablethan the solutions prepared for drug delivery.

Of the more common addition polymers, polyethylene (LDPE), atacticpolypropylene, poly(vinyl acetate) (PVAc), and cis-polyisoprene, are allsoft and easily deform under shear. LDPE is soluble in water andtherefore unusable in the nano-CRC slurry. Atactic polypropylene is bothinsoluble in water and does not adsorb water, which would be perfect forcoating the impregnated particles except that it can only be synthesizedby the Ziegler-Natta polymerization technique, which is much moredifficult and requires more expensive catalysts. PVAc is insoluble inwater and commonly used in paints or protective coatings, which makes ita good candidate for the nano-CRC slurry. PVAc is easily prepared byfree radical polymerization of vinyl acetate monomer. Cis-polyisoprenewould not be useful for this project as it is also difficult tosynthesize.

In an embodiment, the polymer coating of the contact release capsulecomprises PVAc. PVAc is easily synthesized and the monomer units areinexpensive and readily available. Several commercial sources of softpolymer materials are also available. Soft Polymer Systems Inc. offersseveral gel type materials for coatings and paints which may work wellwith the contact release capsules disclosed herein.

In an embodiment, a similar method to that developed by Herrera et al.is used to coat the impregnated particles. In an embodiment, the polymercoating of the contact release capsule comprises pNIPAM or pNIPMAM. Thesmart polymer substances, pNIPAM and pNIPMAM, are both insoluble inwater and non-degradable. They are soft gel-like polymers which easilydeform with shear. The nanoparticle coating process requires the use ofhexane, acetone, and diethyl ether, in all of which glycine is virtuallyinsoluble. The thickness of the coating needs to be optimized to preventglycine diffusion and dissolution from inside the particle, while alsobeing easily penetrable when contacted by the copper wafer surface. ThepNIPAM and pNIPMAM polymers are smart polymers in that they aretemperature sensitive and change from hydrophilic to hydrophobic above33 and 40° C., respectively. This could potentially be advantageous forpost CMP cleans as the temperature sensitivity could be utilized to helpremove the polymer from solution. However, should pNIPAM or pNIPMAM beutilized as the coating on the contact release capsules for a copper CMPslurry, a constant temperature storage and delivery of the product willbe required (most CMP slurries already require constant temperaturestorage, so this is not necessarily an issue). Furthermore, S. R.Pullela found that the pNIPAM material also varies in hardness with thesolution pH. At low pH the pNIPAM exhibits properties of a hard colloid,while at high pH the material is a soft gel, see S. R. Pullela, Ph.D.Dissertation, Texas A&M University (2009). This sensitivity to pH couldalso be utilized to increase shelf life of the nano-CRC slurry byformulating and storing the slurry at a low pH, so the polymer is hardand not easily deformed, completely preventing glycine escape from theparticle. Then, just prior to CMP the slurry can be mixed with asolution to raise the pH and soften the polymer so that it will easilydeform when contacted by the copper wafer surface and allow the glycineto react immediately with the abraded copper pieces. Point of use (POU)slurries, or slurries that are mixed together just prior to beingdispensed onto the platen are quite common, (especially for shallowtrench isolation CMP), and most standard industrial CMP machines areequipped to handle the mixing for these types of slurries.

Once the impregnated particles have been coated with the protectivepolymer material, they need to be dispersed into an aqueous solution.There are a variety of techniques that can be utilized to disperse thecontact release capsules into a solution. In an embodiment, the contactrelease capsules are dispersed into solution by ultrasonication, pHadjustment, and/or addition of various electrolytes to control the ionicstrength of the solution and increase the electrostatic repulsionbetween the particles.

In an embodiment, the copper CMP slurry containing the contact releasecapsules, as disclosed herein, is designed to decrease unwantedcorrosion of the copper surface. In an embodiment, the copper CMP slurrycontaining the contact release capsules, as disclosed herein, isdesigned to maintain adequate and controllable MRR. In an embodiment,the copper CMP slurry containing the contact release capsules, asdisclosed herein, is designed to improve planarization efficiency.

Measurement of the chemical etch rate of the slurry gives a goodindication of whether or not the slurry will corrode the copper surfaceduring CMP, leaving unwanted pits and cracks in the copper wiring. Table1 shows the measured chemical etch rates of typical copper CMP slurryformulations along with the CMP MRR using standard slurry formulationswith alumina nanoparticles. For the most part, solutions with high etchrates have high MRRs, while solutions with low etch rates have low MRRs.The solutions that have high etch rates also cause pitting and corrosionon the copper wafer surface, as is discussed in detail in theliterature. From Table 1, only one possible solution would be adequatefor use in the copper CMP process, that is the solution with glycine,H₂O₂, SDS, and BTA at pH 10.8. This solution has a reasonably lowchemical etch rate, 8.6 nm/min, with a reasonably high MRR, 242 nm/min.However, it takes four chemical additives and a fairly alkaline solutionto get a “good enough” slurry. A slurry with a zero chemical etch rate,and an MRR greater than 250 nm/min would be much more attractive.

In designing a copper CMP slurry using the contact release capsules, asdisclosed herein, the solution pH, silica porosity, glycine loading,polymer type, and polymer thickness parameters may all be varied tooptimize the solution to yield the desired properties during CMP.

TABLE 1 Measured Chemical Etch Rates and CMP MRR for standard aluminaslurry formulations, (data from R.Ihnfeldt PhD Dissertation, Universityof California San Diego, 2008). Chemical Etch Rate CMP MRR AqueousAlumina Slurry Components pH (nm/min) (nm/min) 1 mM KNO₃ 2.9 0.7 4 8.3 04 11.7 2.6 0 1 mM KNO₃, 0.1M Glycine 3.1 1.2 2 8.5 7.6 9 10.0 0 15 1 mMKNO₃, 0.1M Glycine, 0.1 wt % 3.0 45 8 H₂O₂ 8.3 33 287 10.0 14 350 1 mMKNO₃, 0.1M Glycine, 2.0 wt % 3.0 37.5 113 H₂O₂ 8.3 55.5 289 10.0 33.1166 1 mM KNO₃, 0.1M Glycine, 0.1 wt % 3.0 1.6 0 H₂O₂, 0.01 wt % BTA, 0.1mM SDS 8.4 0 11 10.8 8.6 242

The invention is now further described by the following preferredembodiments and examples, which are intended to be illustrative of theinvention, but are not intended to limit the scope or underlyingprinciples in any way.

EXAMPLES Porous Silica Synthesis

In an embodiment, porous silica nanoparticles are synthesized using asimilar method to that described by Choi et al. in Material ResearchSociety Symposium Proceeding, volume 671 (2001), which is herebyincorporated by reference in its entirety. This is a modified Stobermethod, a precipitation technique based on controlled hydrolysis of asilicon alkoxide in a mixture of ethanol, aqueous ammonia and water.Choi et al. found that the addition of glycerol to thewater/ammonia/ethanol mixture produces porous silica nanospheres, wherethe concentration of the glycerol in the mixture can be adjusted to getthe desired porosity. Using this method silica nanoparticles withvarious porosities (greater than 0.4 cm³/g) are possible. Table 2 belowshows the results of various glycerol concentrations on the silicaparticle porosity. For each condition the concentration of ammonia,water, and TEOS was fixed at 0.2M, 3.2M, and 0.2M, respectively.Micropore volume was measured by Mercury Intrusion Analysis. Reactiontime for these experiments was ˜17 hours. The particle size can bevaried by adjusting the reaction time accordingly. Particle sizes weremeasured in an aqueous solution using a dynamic light scatteringtechnique with a ZetaPLUS machine from Brookhaven Instruments Inc., andmeasurements were visually verified by Scanning Electron Microscope(SEM).

TABLE 2 Micropore volume of silica particles synthesized with variousconcentrations of glycerol. Glycerol Concentration (M) Particle Size(nm) Micropore volume (cm³/g) a) 0.01M 169 0.3489 b) 0.05M 199 0.3766 c)0.1M 209 0.3829 d) 0.5M* 251 >0.4 *estimated value, high porosity gaveunreliable results

Impregnation of Silica

In an embodiment, impregnation of the silica nanoparticles is done bythe incipient wetness technique. This method requires dissolving theimpregnate into an aqueous or organic solvent. Then theimpregnate-containing solution is added to the support materialcontaining the same pore volume as the volume of solution that wasadded. Capillary action draws the impregnate solution into the pores.The support material can then be dried and calcined to drive off thevolatile components within the solution, depositing the impregnate inthe pores of the support material.

Table 3 below shows the quantitative SEM-EDX analysis of the 0.3829cm³/g porous silica nanoparticles (synthesized using 0.1M glycerol)before and after glycine loading using a glycine saturated aqueoussolution (25 g/100 ml). The elemental analysis of the particles beforeglycine loading are consistent with the formation of SiO₂, while afterglycine loading the quantity of Nitrogen, Oxygen, and Carbonsignificantly increases, indicating successful particle loading ofglycine crystals (small impurities of Na, Mg, K, and Ca are most likelyfrom the water used to load the glycine).

TABLE 3 SEM-EDX analysis of dried 0.3829 cm³/g porous silicananoparticles a) before and b) after glycine loading using a glycinesaturated aqueous solution (25 g/100 ml). App Intensity Weight % ElementConc. Corrn. Weight % Sigma Atomic % a) C 2.94 0.1983 7.02 1.33 11.14 O71.73 0.6762 50.29 0.90 59.89 Si 82.45 0.9156 42.69 0.78 28.96 Totals100.00 b) C 114.8 0.5119 37.18 1.37 45.96 N 6.09 0.0967 10.44 2.17 11.07O 85.76 0.3746 37.96 1.20 35.22 Na 8.41 0.6449 2.16 0.11 1.40 Mg 1.990.6124 0.54 0.05 0.33 Si 54.32 0.8425 10.69 0.33 5.65 K 0.96 1.0183 0.160.03 0.06 Ca 5.04 0.9700 0.86 0.05 0.32 Totals 100.00

Polymer Coating

In an embodiment, a polymer coating technique to encapsulate theimpregnated nanoparticles is used which is similar to the techniquedeveloped by Herrera et al., in the Journal of Colloid and InterfaceScience, volume 342, issue 540 (2010), which is hereby incorporated byreference in its entirety. This technique uses pNIPAM, which is a smartpolymer substance that is insoluble in water and non-degradable. It is asoft gel-like polymer which easily deforms with shear. The nanoparticlecoating process requires the use of hexane, acetone, and diethyl ether,in all of which glycine is virtually insoluble. The thickness of thecoating can be controlled by adjusting the chemistry and polymerizationreaction time.

Prior to polymer coating, porous particles were loaded with glycineusing a glycine saturated aqueous solution (25 g/100 ml), and dried inan oven at 110° C. overnight. To prepare the particles for polymercoating, they were suspended in a solution of hexane and3-(trimethoxysilyl)propyl methacrylate (MPS), and stirred at roomtemperature for 2 days. The functionalized MPS coated silica particleswere then separated from the solution using centrifugation (3400 rpm for15 min) and washed twice with acetone. The particles were then coatedwith covalently attached pNIPAM through free radical polymerizationusing α,α′-azobisisobutyronitrile (AIBN) initiator and N,N′methylenebisacrylamide (MBA) crosslinking agent. The MPS coated silica particleswere suspended in 20 ml of acetone at ˜0.5% w/v and mixed in a flaskwith 10 ml of a solution of 25% w/v NIPAM in acetone, along with 10 mlof 0.5 g AIBN dissolved in acetone, and 10 ml of 0.125 g MBA dissolvedin acetone. The reaction was sealed and carried out at 60° C. for 9hours under continuous stifling at 100 rpm. After polymerization theparticles were separated by centrifugation at 3400 rpm for 15 minutes,washed twice with diethyl ether/acetone (3:1), and dried at roomtemperature. The coated particles were easily suspended in DI waterusing ultrasonication, and particle sizes were measured by dynamic lightscattering technique using a Brookhaven ZetaPlus machine. Visualverification of the particle sizes was done by SEM, and these resultswere consistent with particle size measurements taken in aqueoussolution, which are listed in Table 4 below. Coating thickness decreasedwith increasing porosity, possibly due to the increased pores on theparticle surface inhibiting the attachment of the coating. The particleswith the lowest porosity (0.3489 cm3/g) had the thickest polymer coatingof ˜50 nm. The particles with similar porosities (0.377 and 0.383 cm³/g)were coated with a ˜35 nm NIPAM film. However, the particles with highporosity >0.4 cm³/g had very little if any polymer coating (<4 nm), asthe increased pores on the surface of the particle may inhibit theattachment of the coating.

TABLE 4 Particle size measurements performed in aqueous solutions usinga dynamic light scattering technique. Polymer Coated Particle Porosity(cm³/g) Porous Particle Size (nm) Size (nm) 0.3489 169 a) 270 0.3766 199b) 269 0.3829 209 c) 277 >0.4 251 d) 255

Although the foregoing description has shown, described, and pointed outthe fundamental novel features of the present teachings, it will beunderstood that various omissions, substitutions, and changes in theform of the detail of the invention as illustrated, as well as the usesthereof, may be made by those skilled in the art, without departing fromthe scope of the present teachings. Consequently, the scope of thepresent teachings should not be limited to the foregoing discussion, butshould be defined by the appended claims. All patents, patentpublications and other documents referred to herein are herebyincorporated by reference in their entirety.

1-21. (canceled)
 22. A slurry comprising contact release capsules and aliquid, wherein the contact release capsule comprises a particle, achemical payload, and an organic polymer coating, wherein: the particlecomprises a pore or pores which are impregnated with the chemicalpayload, the organic polymer coating is present on an outside surface ofthe particle and is configured to contain the chemical payload in thepore or pores, the organic polymer coating is configured to be removablefrom the outside surface of the particle to release the chemical payloadfrom the pore or pores by a shearing contact force with a wafer surfaceduring a polishing process, and the particle has a porosity of equal toor greater than about 0.01 cm³/g.
 23. The slurry of claim 22, whereinthe particle comprises a material selected from the group consisting offumed silica, colloidal silica, fumed alumina, colloidal alumina, ceria,MnO₂, ZnO, TiO₂, polymer and combinations thereof.
 24. The slurry ofclaim 22, wherein the chemical payload comprises a complexing agentselected from the group consisting of organic polymer, alkaline agent,organic amine, and combinations thereof.
 25. The slurry of claim 22,wherein the chemical payload is a compound selected from the groupconsisting of glycine, ethylene-diamine-tetra-acetic-acid, alanine,phthalic acid, citric acid, oxalic acid, acetic acid, tartaric acid,succinic acid, amino acid, ammonium hydroxalate, lactic acid, carboxylicacid, organic amine and combinations thereof.
 26. The slurry of claim22, wherein the organic polymer coating comprises a polymer selectedfrom the group consisting of polyacrylate, polymethacrylate,polyethyleneglycol, poly-L-lysine, poly-vinyl alcohol, polysaccharide,polyethylene, polypropylene, poly-vinyl acetate, polyisoprene, andcombinations thereof.
 27. The slurry of claim 22, wherein the liquidcomprises water.
 28. The slurry of claim 27, wherein the water has a pHin the range of about 2 to about
 12. 29. The slurry of claim 28, furthercomprising an acid, a base, a surfactant, an oxidizer, a corrosioninhibitor, or a combination thereof.
 30. The slurry of claim 22, whereinthe contact release capsules are dispersed into the liquid at aconcentration in the range of about 1% to about 40% by weight, based onthe total weight of the slurry.
 31. The slurry of claim 29, furthercomprising an oxidizer selected from the group consisting of peroxide,oxalic acid, and combinations thereof.
 32. The slurry of claim 29,further comprising a corrosion inhibitor selected from the groupconsisting of benzotriazole, 3-amino-triazole, potassium iodate, andcombinations thereof.
 33. A slurry comprising contact release capsulesand water, wherein the contact release capsule comprises a particle, achemical payload, and an organic polymer coating, wherein: the particlecomprises a pore or pores which are impregnated with the chemicalpayload, the organic polymer coating is present on an outside surface ofthe particle and is configured to contain the chemical payload in thepore or pores, the organic polymer coating comprises polyvinyl acetate,polymethyl methacrylate, or combinations thereof, the organic polymercoating is configured to be removable from the outside surface of theparticle to release the chemical payload from the pore or pores by ashearing contact force with a wafer surface during a chemical mechanicalplanarization process, and the particle has a porosity of equal to orgreater than about 0.01 cm³/g.
 34. The slurry of claim 33, wherein thechemical payload comprises glycine.
 35. The slurry of claim 34, furthercomprising hydrogen peroxide.
 36. The slurry of claim 35, furthercomprising a corrosion inhibitor.
 37. The slurry of claim 36, furthercomprising potassium hydroxide.
 38. A method of planarizing and/orpolishing a wafer surface, comprising: contacting the wafer surface withthe slurry of claim 1; and planarizing and/or polishing the wafersurface using the slurry.
 39. The method of claim 38, wherein the wafersurface comprises at least one material selected from Copper, Tungsten,Tantalum, Tin, Tantalum nitride, Silicon nitride, Aluminum, Nickel,Nickel Phosphor, Nickel nitride, Silver, Gold, Germanium, Sapphire,Selenium, Titanium, Platinum, Ruthenium, and combinations thereof. 40.The method of claim 38, wherein the wafer surface comprises at least onematerial selected from tetraethylorthosilicate, Ni₃Si₄, silica, diamond,SiC, polysilicon, and combinations thereof.
 41. The method of claim 38,wherein the wafer surface comprises Copper, the chemical payloadcomprises glycine, the polymer coating comprises polyvinyl acetate, theparticle comprises silica, and the slurry further comprises hydrogenperoxide.